In a typical fuel cell system, each fuel cell stack has multiple H2 supply valves or injectors to supply hydrogen to the anode side of the PEM fuel cell stack. Multiple injectors are used to accurately control the flow and pressure of hydrogen from idle to full power. If all injectors are closed, no H2 will flow, and the fuel cell power output is zero. If all injectors are open, the maximum amount of H2 will flow and the fuel cell will output maximum power. In the case where the fuel cell system has five injectors and all injectors are sized the same, the next injector is opened when the previous injector(s) are at 100% open. Each injector thus accounts for 20% of full power. The desired H2 flow is checked against a maximum possible flow upper limit based on current temperature and pressure conditions. The minimum value of the desired setpoint and the maximum possible flow is used for the first injector, and the rest of the flow is assigned to the other injectors. The same procedure is used to assign the flow for the second injector and so on.
If one of the injectors fails, the system performance is highly dependent on which of the five injectors fails. If the first injector fails and is not able to open any longer, then any requested flow under 20% will result in no flow. This will cause the fuel cell to cease generating power. If the second injector fails, then operation will be limited between 0-20% and 40%-100%. Likewise, if the third injector fails, then operation will be limited between 0-40% and 60%-100%. Thus, there is a desire to provide a method for the redistribution of H2 flow that overcomes the inherent problems associated with failure of one or more injectors in a fuel cell system, and the limitation of power associated therewith.